tag:theconversation.com,2011:/au/topics/predator-and-prey-36111/articlesPredator and prey – The Conversation2018-06-27T13:42:48Ztag:theconversation.com,2011:article/988742018-06-27T13:42:48Z2018-06-27T13:42:48ZWhere are all the dead pigeons?<figure><img src="https://images.theconversation.com/files/224952/original/file-20180626-112614-1y2jwgo.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=496&amp;fit=clip" /><figcaption><span class="caption">shutterstock</span> </figcaption></figure><p>It may not seem like one of life’s great mysteries, but a quick internet search reveals that people from across the world – London to Hong Kong, Cape Town to Buenos Aires – are asking this same question: for all the pigeons out there in our cities, where are all the dead ones? Alas they’re not pondering the presence of pigeon heaven, but rather, where are all the bodies? </p>
<p>Pigeons are as ubiquitous in the world’s cities as bad traffic, buskers, and late-night takeaways. London alone is estimated to contain more than <a href="http://www.londonpigeons.co.uk/">a million pigeons</a>, inhabiting the many parks and gardens that crisscross its 1,000 square miles. Given these vast numbers – and the fact that an urban pigeon seldom lives for more than three or four years – it’s a wonder why they are not strewn across city streets.</p>
<p>There are several possible reasons for this. First, pigeons are just one part of a wide array of creatures to have adopted our cities as their home. Foxes, rats, gulls, <a href="https://www.rspb.org.uk/birds-and-wildlife/wildlife-guides/bird-a-z/crow-family/">crows and ravens</a> all do a wonderful job of cleaning up any carrion they come across, including deceased pigeons. These species perform inestimable services to the urban ecosystem, reducing human exposure to rotting matter and helping cut the transmission of infectious diseases.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/224687/original/file-20180625-19385-195a28.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=754&amp;fit=clip" srcset="https://images.theconversation.com/files/224687/original/file-20180625-19385-195a28.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=600&amp;h=400&amp;fit=crop&amp;dpr=1 600w, https://images.theconversation.com/files/224687/original/file-20180625-19385-195a28.jpg?ixlib=rb-1.1.0&amp;q=30&amp;auto=format&amp;w=600&amp;h=400&amp;fit=crop&amp;dpr=2 1200w, https://images.theconversation.com/files/224687/original/file-20180625-19385-195a28.jpg?ixlib=rb-1.1.0&amp;q=15&amp;auto=format&amp;w=600&amp;h=400&amp;fit=crop&amp;dpr=3 1800w, https://images.theconversation.com/files/224687/original/file-20180625-19385-195a28.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=754&amp;h=503&amp;fit=crop&amp;dpr=1 754w, https://images.theconversation.com/files/224687/original/file-20180625-19385-195a28.jpg?ixlib=rb-1.1.0&amp;q=30&amp;auto=format&amp;w=754&amp;h=503&amp;fit=crop&amp;dpr=2 1508w, https://images.theconversation.com/files/224687/original/file-20180625-19385-195a28.jpg?ixlib=rb-1.1.0&amp;q=15&amp;auto=format&amp;w=754&amp;h=503&amp;fit=crop&amp;dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">Pigeons are the most common bird in London.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/cute-little-boy-rubber-boots-feeding-367427291?src=CxmlJ70MMAnORWCyWkxRHA-1-10">shutterstock</a></span>
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<p>Alongside these native janitors, domestic cats are equally happy to take care of a dead or injured pigeon. It is estimated that there are <a href="https://www.pfma.org.uk/cat-population-2016">half a million cats living in London alone</a> – roughly two pigeons per cat – and if you’re “lucky” they might bring one home as a present. Whether a resident moggy or some other carnivore, this network of surreptitious street cleaners will usually whisk away any pigeon corpses long before they’re seen by human eyes.</p>
<h2>High-rise hideaways</h2>
<p>Most pigeons, however, don’t simply drop dead on the ground. To understand where pigeons themselves are likely to go when feeling vulnerable or unwell, we need to delve into their origins. The pigeons we see in cities are domestic pigeons who have undergone some serious “rewilding”. They were originally bred as homing pigeons, trained birds who relayed important messages over large distances long before telephones. These pigeons even <a href="https://www.bbc.co.uk/news/uk-scotland-tayside-central-17138990">won prestigious medals</a> in both world wars.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/224684/original/file-20180625-19399-13ecj91.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=754&amp;fit=clip" srcset="https://images.theconversation.com/files/224684/original/file-20180625-19399-13ecj91.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=600&amp;h=400&amp;fit=crop&amp;dpr=1 600w, https://images.theconversation.com/files/224684/original/file-20180625-19399-13ecj91.jpg?ixlib=rb-1.1.0&amp;q=30&amp;auto=format&amp;w=600&amp;h=400&amp;fit=crop&amp;dpr=2 1200w, https://images.theconversation.com/files/224684/original/file-20180625-19399-13ecj91.jpg?ixlib=rb-1.1.0&amp;q=15&amp;auto=format&amp;w=600&amp;h=400&amp;fit=crop&amp;dpr=3 1800w, https://images.theconversation.com/files/224684/original/file-20180625-19399-13ecj91.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=754&amp;h=503&amp;fit=crop&amp;dpr=1 754w, https://images.theconversation.com/files/224684/original/file-20180625-19399-13ecj91.jpg?ixlib=rb-1.1.0&amp;q=30&amp;auto=format&amp;w=754&amp;h=503&amp;fit=crop&amp;dpr=2 1508w, https://images.theconversation.com/files/224684/original/file-20180625-19399-13ecj91.jpg?ixlib=rb-1.1.0&amp;q=15&amp;auto=format&amp;w=754&amp;h=503&amp;fit=crop&amp;dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">This rock pigeon just wants to die with dignity.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/front-view-face-rock-pigeon-facerock-1069354133?src=nx8EtRifn3tLp6adHTNQQA-1-25">shutterstock</a></span>
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<p>Going back further, the original homing pigeons were bred centuries ago from <a href="https://www.rspb.org.uk/birds-and-wildlife/wildlife-guides/bird-a-z/rock-dove">wild rock doves</a>, a species which inhabits sea cliffs and coastal caves. Cities, with their high-rise buildings and elevated ledges, provide ideal nest sites for feral pigeons, and create an environment reminiscent of their ancestral homes. This background means that, when sick or injured, pigeons instinctively retreat to dark, remote places – ventilation systems, attics, building ledges – hoping to remain out of reach and unnoticed by predators. The predators don’t see them, but neither do we: often when pigeons expire, they are in hiding.</p>
<h2>Gone before their time</h2>
<p>But what actually causes a pigeon to die? As they get older, pigeons become more susceptible to disease, and often become slower to react to oncoming predators. It is well-established that when a predator attacks a flock of birds, slower individuals can become isolated from the group, making them easy prey. Dying of old age is not a luxury afforded to most pigeons: as soon as they shows signs of slowness or sickness, many are snapped up by <a href="http://www.bbc.co.uk/earth/story/20150626-the-predator-ruling-uk-city-skies">peregrine falcons</a>, sparrowhawks, or other predators.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/224696/original/file-20180625-19375-l7g61a.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=754&amp;fit=clip" srcset="https://images.theconversation.com/files/224696/original/file-20180625-19375-l7g61a.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=600&amp;h=400&amp;fit=crop&amp;dpr=1 600w, https://images.theconversation.com/files/224696/original/file-20180625-19375-l7g61a.jpg?ixlib=rb-1.1.0&amp;q=30&amp;auto=format&amp;w=600&amp;h=400&amp;fit=crop&amp;dpr=2 1200w, https://images.theconversation.com/files/224696/original/file-20180625-19375-l7g61a.jpg?ixlib=rb-1.1.0&amp;q=15&amp;auto=format&amp;w=600&amp;h=400&amp;fit=crop&amp;dpr=3 1800w, https://images.theconversation.com/files/224696/original/file-20180625-19375-l7g61a.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=754&amp;h=503&amp;fit=crop&amp;dpr=1 754w, https://images.theconversation.com/files/224696/original/file-20180625-19375-l7g61a.jpg?ixlib=rb-1.1.0&amp;q=30&amp;auto=format&amp;w=754&amp;h=503&amp;fit=crop&amp;dpr=2 1508w, https://images.theconversation.com/files/224696/original/file-20180625-19375-l7g61a.jpg?ixlib=rb-1.1.0&amp;q=15&amp;auto=format&amp;w=754&amp;h=503&amp;fit=crop&amp;dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A peregrine falcon with its unfortunate quarry.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/peregrine-falcon-cutting-pigeon-1055065289?src=b8FTrk5gDrMpiR9spDtjRw-1-43">shutterstock</a></span>
</figcaption>
</figure>
<p>One slightly macabre alternative that occurs in big cities, involves <a href="http://jomec.co.uk/thecardiffian/2018/03/20/rspca-warning-two-birds-killed-queen-street/">the netting that often hangs around buildings</a>. Birds can easily fly into it and become entangled: not just old or sick pigeons, but any bird unfortunate enough not to notice it. Netting is usually high above the ground, so after some fruitless struggling dead pigeons usually hang there, away from the scavengers below. </p>
<p>Whether snatched midair by birds of prey, entangled by man made obstacles or alone in a remote corner of a skyscraper’s roof garden, there are many ways that pigeons pass on from this world. But they all take place within an internal urban ecosystem, that, for the most part, is hidden from our sight.</p><img src="https://counter.theconversation.com/content/98874/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Steve Portugal does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>London should be one giant pigeon cemetery, but you rarely see the bodies.Steve Portugal, Reader in Animal Biology and Physiology, Royal HollowayLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/936452018-03-20T19:04:33Z2018-03-20T19:04:33ZAs humans change the world, predators seize the chance to succeed<figure><img src="https://images.theconversation.com/files/211132/original/file-20180320-31602-18wxjjr.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=496&amp;fit=clip" /><figcaption><span class="caption">A boobook enjoys its vantage point, courtesy of humans.</span> <span class="attribution"><span class="source">Simon Cherriman</span>, <span class="license">Author provided</span></span></figcaption></figure><p>If you have ever been to a nature reserve in Africa, you may have been lucky enough to see predators on a kill – maybe something spectacular like lions on a giraffe. The chances are you got to see that because the predators killed the prey right on the road, where you could get up close in your car or safari vehicle. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/211142/original/file-20180320-31627-16wet5p.JPG?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=754&amp;fit=clip" srcset="https://images.theconversation.com/files/211142/original/file-20180320-31627-16wet5p.JPG?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=600&amp;h=450&amp;fit=crop&amp;dpr=1 600w, https://images.theconversation.com/files/211142/original/file-20180320-31627-16wet5p.JPG?ixlib=rb-1.1.0&amp;q=30&amp;auto=format&amp;w=600&amp;h=450&amp;fit=crop&amp;dpr=2 1200w, https://images.theconversation.com/files/211142/original/file-20180320-31627-16wet5p.JPG?ixlib=rb-1.1.0&amp;q=15&amp;auto=format&amp;w=600&amp;h=450&amp;fit=crop&amp;dpr=3 1800w, https://images.theconversation.com/files/211142/original/file-20180320-31627-16wet5p.JPG?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=754&amp;h=566&amp;fit=crop&amp;dpr=1 754w, https://images.theconversation.com/files/211142/original/file-20180320-31627-16wet5p.JPG?ixlib=rb-1.1.0&amp;q=30&amp;auto=format&amp;w=754&amp;h=566&amp;fit=crop&amp;dpr=2 1508w, https://images.theconversation.com/files/211142/original/file-20180320-31627-16wet5p.JPG?ixlib=rb-1.1.0&amp;q=15&amp;auto=format&amp;w=754&amp;h=566&amp;fit=crop&amp;dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Lions gathered on a road in a South African National Park.</span>
<span class="attribution"><span class="source">Bill Bateman</span></span>
</figcaption>
</figure>
<p>But what if this was not just luck? What if lions had greater hunting success along a road because their prey slip on the tarmac, stumble and fall, thus becoming a meal? The road – a human intrusion in a natural world – could be increasing the predators’ hunting success.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/xGe1Wm83kkI?wmode=transparent&amp;start=0" frameborder="0" allowfullscreen></iframe>
<figcaption><span class="caption">Road kill.</span></figcaption>
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<p>This intriguing idea led us to wonder if there were other examples in which human structures or environments might benefit predators – a group of animals that would otherwise appear to want as little to do with humans and their world as possible.</p>
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<em>
<strong>
Read more:
<a href="http://theconversation.com/you-scratch-my-back-the-beneficial-and-not-so-beneficial-relationships-between-organisms-57120">You scratch my back... the beneficial (and not so beneficial) relationships between organisms</a>
</strong>
</em>
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<hr>
<p>Ecosystems are dynamic, which means that new ones can arise when species occur in combinations and numbers that have not happened before. While we often (rightly) have a very negative view of our impact on the natural world, sometimes organisms can surprise us by taking advantage of what we do and creating a successful space for themselves in a human world.</p>
<p>Once we started looking, we found other examples of predators exploiting these niches. We found four ways, with much overlap, that predators take advantage of human habitats to improve their hunting success. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/211141/original/file-20180320-31599-gxzlep.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=754&amp;fit=clip" srcset="https://images.theconversation.com/files/211141/original/file-20180320-31599-gxzlep.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=600&amp;h=454&amp;fit=crop&amp;dpr=1 600w, https://images.theconversation.com/files/211141/original/file-20180320-31599-gxzlep.jpg?ixlib=rb-1.1.0&amp;q=30&amp;auto=format&amp;w=600&amp;h=454&amp;fit=crop&amp;dpr=2 1200w, https://images.theconversation.com/files/211141/original/file-20180320-31599-gxzlep.jpg?ixlib=rb-1.1.0&amp;q=15&amp;auto=format&amp;w=600&amp;h=454&amp;fit=crop&amp;dpr=3 1800w, https://images.theconversation.com/files/211141/original/file-20180320-31599-gxzlep.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=754&amp;h=570&amp;fit=crop&amp;dpr=1 754w, https://images.theconversation.com/files/211141/original/file-20180320-31599-gxzlep.jpg?ixlib=rb-1.1.0&amp;q=30&amp;auto=format&amp;w=754&amp;h=570&amp;fit=crop&amp;dpr=2 1508w, https://images.theconversation.com/files/211141/original/file-20180320-31599-gxzlep.jpg?ixlib=rb-1.1.0&amp;q=15&amp;auto=format&amp;w=754&amp;h=570&amp;fit=crop&amp;dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A world of opportunities.</span>
</figcaption>
</figure>
<p>First, certain animal species follow human settlements and can provide a completely new food source for predators. Rodents (rats and mice) and invasive birds (such as sparrows or starlings) exploit resources around towns. Pets and livestock are also commonly taken by predators such as bears, wolves, foxes and dingoes.</p>
<figure class="align-right ">
<img alt="" src="https://images.theconversation.com/files/211149/original/file-20180320-31627-1a7hk3a.JPG?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=237&amp;fit=clip" srcset="https://images.theconversation.com/files/211149/original/file-20180320-31627-1a7hk3a.JPG?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=600&amp;h=900&amp;fit=crop&amp;dpr=1 600w, https://images.theconversation.com/files/211149/original/file-20180320-31627-1a7hk3a.JPG?ixlib=rb-1.1.0&amp;q=30&amp;auto=format&amp;w=600&amp;h=900&amp;fit=crop&amp;dpr=2 1200w, https://images.theconversation.com/files/211149/original/file-20180320-31627-1a7hk3a.JPG?ixlib=rb-1.1.0&amp;q=15&amp;auto=format&amp;w=600&amp;h=900&amp;fit=crop&amp;dpr=3 1800w, https://images.theconversation.com/files/211149/original/file-20180320-31627-1a7hk3a.JPG?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=754&amp;h=1131&amp;fit=crop&amp;dpr=1 754w, https://images.theconversation.com/files/211149/original/file-20180320-31627-1a7hk3a.JPG?ixlib=rb-1.1.0&amp;q=30&amp;auto=format&amp;w=754&amp;h=1131&amp;fit=crop&amp;dpr=2 1508w, https://images.theconversation.com/files/211149/original/file-20180320-31627-1a7hk3a.JPG?ixlib=rb-1.1.0&amp;q=15&amp;auto=format&amp;w=754&amp;h=1131&amp;fit=crop&amp;dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Lions have learned to use cowbells to locate livestock, and may have increased hunting success using gravel and tarmac roads to chase prey.</span>
<span class="attribution"><span class="source">Trish Fleming</span></span>
</figcaption>
</figure>
<p>Second, potential prey species often gather around artificial resources, reducing commute times for predators and increasing their hunting success. For example, European kestrels ambush populations of bats and swifts as they leave their roosts in building ventilation. Two species of sea lion have learned to travel 100km up the Columbia River in the United States to <a href="http://www.oregonlive.com/environment/index.ssf/2011/04/at_the_foot_of_the_bonneville.html">hunt masses of migrating salmon</a> that gather at fish ladders (structures that help fish go over or around dams or other barriers when migrating upriver to spawn) over the Bonneville Dam. Brown bears, meanwhile, <a href="https://www.youtube.com/watch?v=DrOqYtv6wOE">hunt at fish weirs</a>, trapping congregations of fish against these to prevent their escape. </p>
<p>Third, structures we build or things we do can make prey species more vulnerable. African wild dogs take down larger prey when they chase them into fences, and dingoes exploit roadkill along major highways. Horse-eye jack fish ambush prey around dock pilings that interrupt the synchronised escape behaviour of the fish schools. Peregrine falcons in New York city hunt at night as they have more success catching pigeons that are bedazzled by skyscraper lights. Lions have learned to use cowbells to locate livestock. Here in Australia wedge-tailed eagles follow harvesters on farms to <a href="http://www.abc.net.au/news/rural/2013-12-05/flying-foxes-in-the-wheatbelt/5138450">catch animals flushed out by the machinery</a>.</p>
<p>Finally, some predators also use resources that we provide as tools to aid their hunting. Some birds use human refuse to <a href="https://www.youtube.com/watch?v=kSClutBjeHk">lure fish to their doom</a>. Many raptors use lampposts and aerials as perches, increasing their hunting success. Larger species such as <a href="http://robertefuller.blogspot.com.au/2012/09/cheetah-perch.html">cheetah</a> and <a href="https://africageographic.com/blog/leopard-uses-car-cover-hunting/">leopards</a> similarly exploit our presence to hunt more successfully.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/211091/original/file-20180320-31611-1g2pp22.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=754&amp;fit=clip" srcset="https://images.theconversation.com/files/211091/original/file-20180320-31611-1g2pp22.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=600&amp;h=402&amp;fit=crop&amp;dpr=1 600w, https://images.theconversation.com/files/211091/original/file-20180320-31611-1g2pp22.jpg?ixlib=rb-1.1.0&amp;q=30&amp;auto=format&amp;w=600&amp;h=402&amp;fit=crop&amp;dpr=2 1200w, https://images.theconversation.com/files/211091/original/file-20180320-31611-1g2pp22.jpg?ixlib=rb-1.1.0&amp;q=15&amp;auto=format&amp;w=600&amp;h=402&amp;fit=crop&amp;dpr=3 1800w, https://images.theconversation.com/files/211091/original/file-20180320-31611-1g2pp22.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=754&amp;h=505&amp;fit=crop&amp;dpr=1 754w, https://images.theconversation.com/files/211091/original/file-20180320-31611-1g2pp22.jpg?ixlib=rb-1.1.0&amp;q=30&amp;auto=format&amp;w=754&amp;h=505&amp;fit=crop&amp;dpr=2 1508w, https://images.theconversation.com/files/211091/original/file-20180320-31611-1g2pp22.jpg?ixlib=rb-1.1.0&amp;q=15&amp;auto=format&amp;w=754&amp;h=505&amp;fit=crop&amp;dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Osprey on aerial.</span>
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<p>Only a few studies have tried to quantify the benefits of human environments for predators, identifying how they experience increased hunting success, reduced energy expenditure, or increased reproductive output. Such benefits can ultimately lead to increased population sizes, as has happened with the <a href="http://www.battaly.com/nehw/AmericanKestrel/news/">New York kestrel population</a> and <a href="https://chicagotonight.wttw.com/2017/12/27/why-are-coyotes-thriving-chicago-area">Chicago’s coyotes</a>. </p>
<p>We predict that some predators are likely to become more abundant in our lives, which could have both positive and negative implications. For example, they are important <a href="https://academic.oup.com/cz/advance-article/doi/10.1093/cz/zox039/3895746">biocontrol agents</a> and do a great job of suppressing rodent populations. However, interactions with large predators can be <a href="https://www.theguardian.com/environment/2017/may/21/video-california-sea-lion-grabs-girl-from-dock">dangerous</a> for humans.</p>
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<figcaption><span class="caption">Letting humans do the hard work.</span></figcaption>
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<p>Predators can be vital for maintaining a balanced ecosystem. However, predator species can have a huge effect on their environment, even when there are only a few of them about. Predator species can easily become invasive animals, as we have seen with the introduction of cats into Australia or <a href="https://www.sciencealert.com/guam-s-plague-of-snakes-is-having-a-devastating-impact-on-the-trees">brown tree snakes onto the island of Guam</a>. </p>
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Read more:
<a href="http://theconversation.com/the-hunt-a-natural-history-series-that-challenges-us-to-side-with-the-predators-49830">The Hunt: a natural history series that challenges us to side with the predators</a>
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<p>These predators have had devastating consequences for whole ecosystems, and our actions may be unwittingly increasing their advantages over prey species, as has been made evident by ravens using human-built perches to predate heavily on desert tortoises. Similarly, animals using road underpasses are more vulnerable to introduced red foxes as the foxes - clever animals - soon learn to wait at the underpass exit for a meal delivery. </p>
<p>Our presence and the way we alter our environment can therefore thwart conservation of threatened species, despite our best attempts. We need to carefully consider how we influence our environment, and be on the lookout for instances where predators are making use of novel niches to exploit prey species. Even the smallest changes we make can affect a whole landscape and can make prey animals more vulnerable.</p><img src="https://counter.theconversation.com/content/93645/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>The authors do not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>From falcons that hunt by the light of skyscrapers, to bears that sit in wait at weirs, animals are using human structures to help them catch a meal.Bill Bateman, Senior Lecturer, Curtin UniversityTrish Fleming, Associate Professor, Murdoch UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/912882018-02-07T00:03:26Z2018-02-07T00:03:26ZHow bombardier beetles survive being eaten – and other amazing animal defence mechanisms<p>In Disney’s film version of Pinnochio, the boy-puppet rescues his creator Geppetto by lighting a fire inside Monstro the whale, who has swallowed them both. The fire causes the whale to sneeze, freeing Pinnochio and Geppetto from their gastric prison.</p>
<p>Before you dismiss this getaway as incredible fantasy, consider that new research shows that a kind of fire in the belly can actually be an effective strategy for escaping predators in the real world. In fact, the animal kingdom is full of amazing examples of unusual defence mechanisms that help small creatures avoid a nasty fate.</p>
<p>In a new paper <a href="http://rsbl.royalsocietypublishing.org/lookup/doi/10.1098/rsbl.2017.0647">in Biology Letters</a>, scientists at Kobe University in Japan describe how bombardier beetles can survive being eaten by a toad by releasing a hot chemical spray that makes the hungry amphibian vomit.</p>
<p>Bombardier beetles are so-named because, when threatened, they emit a boiling, irritating substance from their backsides <a href="http://news.bbc.co.uk/2/hi/science/nature/422599.stm">with remarkable accuracy</a>, to deter potential predators. They produce the caustic mixture by <a href="https://www.wired.com/2014/05/absurd-creature-of-the-week-bombardier-beetle/">combining hydrogen peroxide, hydroquinones and chemical catalysts</a> in a specially reinforced chamber at the base of their abdomen, which shields the beetle’s own organs from the resulting explosive reaction.</p>
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<p><a href="http://rsbl.royalsocietypublishing.org/lookup/doi/10.1098/rsbl.2017.0647">The Japanese researchers</a> fed two different species of bombardier beetles to captive toads. They were then able to confirm that the beetles used their weapon inside the toads by listening carefully for the explosive pop that accompanies each discharge. </p>
<p>Toads are ambush predators, quite used to swallowing first and asking questions later. When they start to feel a dose of diner’s remorse, they can literally turn <a href="https://indianapublicmedia.org/amomentofscience/how-to-heave-your-guts/">their stomachs inside out and scrape out the contents</a>, rather than suffering meekly from indigestion. Many of the toads in this experiment did just that, disgorging the beetles up to 107 minutes after ingestion. Remarkably, the ejected beetles all survived.</p>
<p>In a further experiment, the researchers poked beetles with forceps to deplete their spray reserves. Compared to those with full tanks of fuel, the exhausted beetles were much less likely to be ejected. This showed that it really was their chemical arsenals that saved them, rather than just their taste or behaviour in the gut.</p>
<figure> <img src="https://media.giphy.com/media/26DN4S3rQgsgvzEY0/giphy.gif"><figcaption>“I guess I’ll die another day.” Sugiura &amp; Sato, Kobe University</figcaption></figure>
<p>The bombardier beetle is of course not the only animal escape artist. The diverse getaway tactics of animals are a testament to the fascinating creativity of evolution. Subject to millions of years of abuse and exploitation by predators, natural selection has shaped an array of ingenious strategies for cheating death in the face of would-be devourers.</p>
<h2>Animal Houdinis</h2>
<p>Some examples are probably familiar to most people. For instance, many lizards drop their tails to distract a predator or <a href="https://academic.oup.com/bioscience/article/59/8/728/256547">escape from its venom</a>. But others are more exotic. Sea cucumbers don’t have tails so they <a href="http://echinoblog.blogspot.ca/2012/01/sea-cucumber-evisceration-defense.html">eject and regenerate their internal organs instead</a>. Loud sounds (<a href="http://thatslifesci.com.s3-website-us-east-1.amazonaws.com/2016-12-26-How-Pistol-Shrimp-Kill-With-Bubbles-AStrauss/">such as the “gunshots” of snapping shrimp</a>) and bright colours (as on <a href="https://www.ucpress.edu/ebook.php?isbn=9780520952461">banded wing grasshoppers</a>) are also effective means of <a href="https://pdfs.semanticscholar.org/5742/afd010a4e1b889d1097f28f6f5741f10d33e.pdf">startling predators</a>. Mantid insects unite movement, sound and colour in an elaborate display that can stop an attack or at least give them a chance to escape.</p>
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<p>Some animals fight back, such as the frogs that can <a href="http://rsbl.royalsocietypublishing.org/content/4/4/355">erect sharp bony splinters</a> from their claws that <a href="https://www.newscientist.com/article/dn13991-horror-frog-breaks-own-bones-to-produce-claws/">pierce their own skin</a>, like X-Men’s Wolverine. Other animals, including <a href="https://doi.org/10.1098%252Frspb.2001.1708">the mimic octopus</a>, prefer to pretend to be being dangerous, <a href="https://www.nature.com/scitable/blog/accumulating-glitches/the_mimic_octopus_master_of">adopting the appearance of more deadly prey</a> when threatened.</p>
<p>The stunning variety of defensive mechanisms would be impressive even if we only counted variations of chemical warfare, similar to the bombardier beetle’s steam treatment. There are the defensive toxins in <a href="https://www.nationalgeographic.com/animals/fish/group/pufferfish/">pufferfish</a> and <a href="http://www.bbc.com/earth/story/20150422-the-worlds-most-poisonous-animal">poison arrow frogs</a>, the nauseating <a href="https://www.newscientist.com/article/mg12717282-900-science-the-seven-deadly-smells-of-a-skunk/">odours of skunks</a>, the charmingly named but actually revolting <a href="http://www.bbc.com/earth/story/20150623-millipedes-use-chemical-weapons">repugnatorial glands of some millipedes</a>, and the <a href="http://www.nydailynews.com/life-style/vomit-bird-throws-defense-predators-eurasian-roller-nestlings-emit-foul-smelling-fluid-protection-article-1.1037423">projectile vomiting</a> and <a href="https://wildfowl.wwt.org.uk/index.php/wildfowl/article/view/562">faecal egg decorating</a> of some birds.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/205061/original/file-20180206-14107-1lzimnd.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=754&amp;fit=clip" srcset="https://images.theconversation.com/files/205061/original/file-20180206-14107-1lzimnd.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=600&amp;h=398&amp;fit=crop&amp;dpr=1 600w, https://images.theconversation.com/files/205061/original/file-20180206-14107-1lzimnd.jpg?ixlib=rb-1.1.0&amp;q=30&amp;auto=format&amp;w=600&amp;h=398&amp;fit=crop&amp;dpr=2 1200w, https://images.theconversation.com/files/205061/original/file-20180206-14107-1lzimnd.jpg?ixlib=rb-1.1.0&amp;q=15&amp;auto=format&amp;w=600&amp;h=398&amp;fit=crop&amp;dpr=3 1800w, https://images.theconversation.com/files/205061/original/file-20180206-14107-1lzimnd.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=754&amp;h=501&amp;fit=crop&amp;dpr=1 754w, https://images.theconversation.com/files/205061/original/file-20180206-14107-1lzimnd.jpg?ixlib=rb-1.1.0&amp;q=30&amp;auto=format&amp;w=754&amp;h=501&amp;fit=crop&amp;dpr=2 1508w, https://images.theconversation.com/files/205061/original/file-20180206-14107-1lzimnd.jpg?ixlib=rb-1.1.0&amp;q=15&amp;auto=format&amp;w=754&amp;h=501&amp;fit=crop&amp;dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">I wouldn’t eat me if I were you.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/strawberry-poison-dart-frog-dendrobates-pumilio-110478725?src=wsqFvxedepyW5_6CPNI-NQ-1-3">Maiquez/Shutterstock</a></span>
</figcaption>
</figure>
<p>Why should nature have created such an impressive array of defensive tactics? One possible explanation can be summarised as the <a href="http://evosophos.com/life-dinner-principle/">life-dinner principle</a>, articulated by biologists <a href="http://rspb.royalsocietypublishing.org/content/205/1161/489">Richard Dawkins and John Krebs in the late 1970s</a>. The argument is that predator and prey often face asymmetrical selection pressures, meaning that the stakes are different for the two competitors. If a predator fails to capture its target, it loses dinner, but if the prey fails to escape, it loses its life. Because the stakes are greater for prey, we shouldn’t be surprised they have developed so many impressive defences.</p>
<p>Understanding nature’s tremendous capacity to adapt should make us be careful. Humans interact with other organisms all the time, and usually we’re the predators. When we try to take action against other creatures to stop them spreading disease or eating crops, we should be mindful that evolutionary innovation can produce remarkable adaptations. For example, our widespread use of <a href="https://www.myjoyonline.com/lifestyle/2018/february-3rd/high-levels-of-antibiotic-resistance-found-worldwide-who.php">antibiotics</a> and <a href="https://guardian.ng/features/malaria-cases-rise-as-insecticide-resistance-spreads/">pesticides</a> has spurred the evolution of organisms that are resistant to these methods.</p>
<p>Only by having a healthy respect for the relentless power of evolution can we hope to generate sustainable solutions to these kinds of problems. If we grow complacent and inattentive, we may some day soon find ourselves facing newly evasive diseases and pests, sputtering to breathe and dyspeptic amid all the fire and smoke in our bellies.</p><img src="https://counter.theconversation.com/content/91288/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Luc Bussiere does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Meet the brawny bug with a concoction so caustic it'll make a toad vomit.Luc Bussiere, Lecturer in Biological Sciences, University of StirlingLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/864502017-10-30T22:51:12Z2017-10-30T22:51:12ZEvery day is Halloween for these eerie insects<figure><img src="https://images.theconversation.com/files/192349/original/file-20171029-13309-1qcpwe8.jpeg?ixlib=rb-1.1.0&amp;rect=0%2C856%2C3939%2C2012&amp;q=45&amp;auto=format&amp;w=496&amp;fit=clip" /><figcaption><span class="caption">Gory and gross, insects use disguises to improve their odds of survival.</span> <span class="attribution"><span class="source">(Pixabay)</span></span></figcaption></figure><p>With Halloween upon us, it’s worth remembering that living things take part in similar costume parties all year long, adopting weird and wonderful forms. </p>
<p>Though rather than a haul of candy, organisms might earn the chance to live, prosper and mate. It’s all part of evolution, the principle where the fittest individuals pass their genes onto the next generation. </p>
<p>Insects readily display the strange products of evolution. They have crawled their way across the Earth for at least <a href="https://www.nature.com/nature/journal/v427/n6975/abs/nature02291.html">400 million years</a>, and rapidly develop from egg to adult. </p>
<p>Over millions of generations, insects have developed a multitude of weird and wonderful ways to find food, attract mates, hide or defend themselves from predators. All these adaptations allow an individual’s genes to persist in the population. </p>
<p>There are more than a <a href="https://theconversation.com/why-we-should-learn-to-love-all-insects-not-just-the-ones-that-work-for-us-49925">million species</a> of insects, and some of them have some pretty ingenious disguises. </p>
<h2>What’s that on your head?</h2>
<p>In a pinch, an unusual headpiece can pass for a Halloween costume. With minimal effort, a regular Joe can be transformed into a construction worker, mouse or witch. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/192337/original/file-20171029-13327-14szmdv.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=754&amp;fit=clip" srcset="https://images.theconversation.com/files/192337/original/file-20171029-13327-14szmdv.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=600&amp;h=452&amp;fit=crop&amp;dpr=1 600w, https://images.theconversation.com/files/192337/original/file-20171029-13327-14szmdv.jpg?ixlib=rb-1.1.0&amp;q=30&amp;auto=format&amp;w=600&amp;h=452&amp;fit=crop&amp;dpr=2 1200w, https://images.theconversation.com/files/192337/original/file-20171029-13327-14szmdv.jpg?ixlib=rb-1.1.0&amp;q=15&amp;auto=format&amp;w=600&amp;h=452&amp;fit=crop&amp;dpr=3 1800w, https://images.theconversation.com/files/192337/original/file-20171029-13327-14szmdv.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=754&amp;h=568&amp;fit=crop&amp;dpr=1 754w, https://images.theconversation.com/files/192337/original/file-20171029-13327-14szmdv.jpg?ixlib=rb-1.1.0&amp;q=30&amp;auto=format&amp;w=754&amp;h=568&amp;fit=crop&amp;dpr=2 1508w, https://images.theconversation.com/files/192337/original/file-20171029-13327-14szmdv.jpg?ixlib=rb-1.1.0&amp;q=15&amp;auto=format&amp;w=754&amp;h=568&amp;fit=crop&amp;dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">This ‘Mad Hatterpillar’ stacks its old heads.</span>
<span class="attribution"><span class="source">(Flickr/Natalie Tapson)</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc-sa/4.0/">CC BY-NC-SA</a></span>
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<p>But some species are a little more macabre. One species of caterpillar, the gum leaf skeletonizer (<em>Uraba lugens</em>), dons a “hat” of heads, a conical ornament made up of its own discarded head capsules, one stacked on top of the next. </p>
<p>The disguise is gory but effective. Researchers studying this grotesque accessory <a href="https://peerj.com/articles/1714/?utm_source=TrendMD&amp;utm_campaign=PeerJ_TrendMD_0&amp;utm_medium=TrendMD">have found that it helps the caterpillar ward off attack by confusing its predators</a>, making it a truly a functional fashion item. </p>
<h2>Trick or treat, smell my feet</h2>
<p>The orchid mantis (<em>Hymenopus coronatus</em>) prefers a simple trick to get its treat.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/192338/original/file-20171029-13340-p6mmwd.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=754&amp;fit=clip" srcset="https://images.theconversation.com/files/192338/original/file-20171029-13340-p6mmwd.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=600&amp;h=400&amp;fit=crop&amp;dpr=1 600w, https://images.theconversation.com/files/192338/original/file-20171029-13340-p6mmwd.jpg?ixlib=rb-1.1.0&amp;q=30&amp;auto=format&amp;w=600&amp;h=400&amp;fit=crop&amp;dpr=2 1200w, https://images.theconversation.com/files/192338/original/file-20171029-13340-p6mmwd.jpg?ixlib=rb-1.1.0&amp;q=15&amp;auto=format&amp;w=600&amp;h=400&amp;fit=crop&amp;dpr=3 1800w, https://images.theconversation.com/files/192338/original/file-20171029-13340-p6mmwd.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=754&amp;h=503&amp;fit=crop&amp;dpr=1 754w, https://images.theconversation.com/files/192338/original/file-20171029-13340-p6mmwd.jpg?ixlib=rb-1.1.0&amp;q=30&amp;auto=format&amp;w=754&amp;h=503&amp;fit=crop&amp;dpr=2 1508w, https://images.theconversation.com/files/192338/original/file-20171029-13340-p6mmwd.jpg?ixlib=rb-1.1.0&amp;q=15&amp;auto=format&amp;w=754&amp;h=503&amp;fit=crop&amp;dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">This beautiful mantis is a bloodthirsty predator in disguise.</span>
<span class="attribution"><span class="source">(Shutterstock)</span></span>
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</figure>
<p>Found in the rainforests of Southeast Asia, this species <a href="http://www.cell.com/current-biology/abstract/S0960-9822(15)01421-9">looks undeniably like an orchid</a>. Its hind pairs of legs are greatly flattened and heart-shaped, looking uncannily like petals. Many smaller insects <a href="http://www.journals.uchicago.edu/doi/abs/10.1086/673858">find these mantises even more attractive than the orchids they mimic</a>. </p>
<p>But get too close and the orchid mantis doesn’t smell too sweet. It uses its front legs to hunt, aggressively snatching and eating insects looking for a treat of nectar or pollen. </p>
<h2>Ssssscary stuff</h2>
<p>For some people, Halloween is all about terror. </p>
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<figcaption>
<span class="caption">Caterpillars can be scary too.</span>
<span class="attribution"><span class="source">(Andreas Kay/Flickr)</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc-sa/4.0/">CC BY-NC-SA</a></span>
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<p>The larval form of the tropical moth <em>Hemeroplanes triptolemus</em> falls neatly into that category. It is a harmless caterpillar, but when threatened does a <a href="https://www.youtube.com/watch?v=1XUSYv7xgPo">compelling impersonation of a snake</a>.</p>
<p>Birds love to eat caterpillars, but snakes love to eat birds. So, when this larva is <em>in cognito</em>, it wins the costume contest every time. </p>
<h2>That one costume that goes a little too far</h2>
<p>Inevitably at a Halloween party, someone with an unusual sense of humour will wear a costume that just isn’t appropriate. </p>
<p>In the insect world, the inappropriate costume prize might go to the caterpillars who pose as bird feces. Caterpillars are a pretty ideal snack for birds — they often occur in high densities, are high in fats and are easy to catch. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/192340/original/file-20171029-13331-1hoeyhs.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=754&amp;fit=clip" srcset="https://images.theconversation.com/files/192340/original/file-20171029-13331-1hoeyhs.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=600&amp;h=450&amp;fit=crop&amp;dpr=1 600w, https://images.theconversation.com/files/192340/original/file-20171029-13331-1hoeyhs.jpg?ixlib=rb-1.1.0&amp;q=30&amp;auto=format&amp;w=600&amp;h=450&amp;fit=crop&amp;dpr=2 1200w, https://images.theconversation.com/files/192340/original/file-20171029-13331-1hoeyhs.jpg?ixlib=rb-1.1.0&amp;q=15&amp;auto=format&amp;w=600&amp;h=450&amp;fit=crop&amp;dpr=3 1800w, https://images.theconversation.com/files/192340/original/file-20171029-13331-1hoeyhs.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=754&amp;h=566&amp;fit=crop&amp;dpr=1 754w, https://images.theconversation.com/files/192340/original/file-20171029-13331-1hoeyhs.jpg?ixlib=rb-1.1.0&amp;q=30&amp;auto=format&amp;w=754&amp;h=566&amp;fit=crop&amp;dpr=2 1508w, https://images.theconversation.com/files/192340/original/file-20171029-13331-1hoeyhs.jpg?ixlib=rb-1.1.0&amp;q=15&amp;auto=format&amp;w=754&amp;h=566&amp;fit=crop&amp;dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">This giant swallowtail caterpillar is hidden in plain sight.</span>
<span class="attribution"><span class="source">(Flickr)</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc-sa/4.0/">CC BY-NC-SA</a></span>
</figcaption>
</figure>
<p>Caterpillars can try to avoid predatory birds by masquerading as bird droppings. There are very few larger organisms that feed on bird feces, so this disguise is a useful strategy to avoid being eaten. It is such an effective disguise, in fact, that many species are known to <a href="http://www.sciencedirect.com/science/article/pii/S0003347215001463">use this strategy</a>, including many species of charismatic swallowtail butterflies. </p>
<h2>A thorn between two thorns</h2>
<p>Have you ever shown up at a party and found someone else was wearing the same costume? It’s embarrassing. But some insects use this otherwise awkward situation to keep a low profile.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/192490/original/file-20171030-18693-18f4a97.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=754&amp;fit=clip" srcset="https://images.theconversation.com/files/192490/original/file-20171030-18693-18f4a97.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=600&amp;h=900&amp;fit=crop&amp;dpr=1 600w, https://images.theconversation.com/files/192490/original/file-20171030-18693-18f4a97.jpg?ixlib=rb-1.1.0&amp;q=30&amp;auto=format&amp;w=600&amp;h=900&amp;fit=crop&amp;dpr=2 1200w, https://images.theconversation.com/files/192490/original/file-20171030-18693-18f4a97.jpg?ixlib=rb-1.1.0&amp;q=15&amp;auto=format&amp;w=600&amp;h=900&amp;fit=crop&amp;dpr=3 1800w, https://images.theconversation.com/files/192490/original/file-20171030-18693-18f4a97.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=754&amp;h=1131&amp;fit=crop&amp;dpr=1 754w, https://images.theconversation.com/files/192490/original/file-20171030-18693-18f4a97.jpg?ixlib=rb-1.1.0&amp;q=30&amp;auto=format&amp;w=754&amp;h=1131&amp;fit=crop&amp;dpr=2 1508w, https://images.theconversation.com/files/192490/original/file-20171030-18693-18f4a97.jpg?ixlib=rb-1.1.0&amp;q=15&amp;auto=format&amp;w=754&amp;h=1131&amp;fit=crop&amp;dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Echenopa binotata, a bug that pretends to be a thorn.</span>
<span class="attribution"><span class="source">(Creative Commons)</span></span>
</figcaption>
</figure>
<p>Take for example species of treehopper in the genus <em>Enchenopa</em>. These small insects feed on sap and are found throughout <a href="https://bugguide.net/node/view/7359">eastern and continental North America</a>. </p>
<p>From a distance, species in this genus are nearly indistinguishable from thorns. The insects themselves are not as sharp as thorns, but this disguise allows them to seamlessly blend into their surroundings while enjoying a good feed. </p>
<h2>A killer among us</h2>
<p>In the movie <em>Murder on the Orient Express</em>, a killer lurks among a group of stranded passengers, blending in with his fellow travellers. Some species of <a href="http://www.sciencedirect.com/science/article/pii/S0960982217301987">staphylinid beetles</a> make use of a similar strategy. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/192494/original/file-20171030-18700-1h4j09s.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=754&amp;fit=clip" srcset="https://images.theconversation.com/files/192494/original/file-20171030-18700-1h4j09s.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=600&amp;h=390&amp;fit=crop&amp;dpr=1 600w, https://images.theconversation.com/files/192494/original/file-20171030-18700-1h4j09s.jpg?ixlib=rb-1.1.0&amp;q=30&amp;auto=format&amp;w=600&amp;h=390&amp;fit=crop&amp;dpr=2 1200w, https://images.theconversation.com/files/192494/original/file-20171030-18700-1h4j09s.jpg?ixlib=rb-1.1.0&amp;q=15&amp;auto=format&amp;w=600&amp;h=390&amp;fit=crop&amp;dpr=3 1800w, https://images.theconversation.com/files/192494/original/file-20171030-18700-1h4j09s.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=754&amp;h=489&amp;fit=crop&amp;dpr=1 754w, https://images.theconversation.com/files/192494/original/file-20171030-18700-1h4j09s.jpg?ixlib=rb-1.1.0&amp;q=30&amp;auto=format&amp;w=754&amp;h=489&amp;fit=crop&amp;dpr=2 1508w, https://images.theconversation.com/files/192494/original/file-20171030-18700-1h4j09s.jpg?ixlib=rb-1.1.0&amp;q=15&amp;auto=format&amp;w=754&amp;h=489&amp;fit=crop&amp;dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A staphylinid beetle that likes to infiltrate ant nests. Avoid inviting to your next costume party.</span>
<span class="attribution"><span class="source">(Shutterstock)</span></span>
</figcaption>
</figure>
<p>And then, they eat the brood young of their hosts.</p>
<p>This Halloween, after the jack o'lanterns have flickered out and the costumed children have all returned home, remember that there may still be some masters of disguise lurking in the shadows.</p><img src="https://counter.theconversation.com/content/86450/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Paul Manning does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Some insects wear gory disguises and macabre masks year round, not just at Halloween.Paul Manning, Postdoctoral fellow, Dalhousie UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/792822017-06-28T14:58:07Z2017-06-28T14:58:07ZHow badly implemented land reform can affect wildlife: a Zimbabwean case study<figure><img src="https://images.theconversation.com/files/175855/original/file-20170627-24767-5g8a9y.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=496&amp;fit=clip" /><figcaption><span class="caption">Land reform is thought to have caused the cheetah numbers to fall by 85% in Zimbabwe.</span> <span class="attribution"><span class="source">Sam Williams</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>Large carnivores are <a href="https://doi.org/10.1126/science.1241484">in decline</a> all over the world. Threats like <a href="https://doi.org/10.1098/rsos.161090">persecution</a> and loss of both <a href="https://doi.org/10.1073/pnas.1611122114">prey and habitat</a> are key contributors. The planet’s top biodiversity hotspots have already <a href="https://doi.org/10.1038/35002501">lost around 90%</a> of their primary (undisturbed) vegetation, <a href="https://doi.org/10.1641/0006-3568(2002)052%5B0143:PCAUDF%5D2.0.CO;2">driven by factors like</a> growth of infrastructure, agriculture and the removal of natural resources.</p>
<p>These are some of the key factors that have caused the number of wild lions across the globe to <a href="http://www.iucnredlist.org/details/full/15951/0">fall by over 40%</a> in the past two decades, and have resulted in <a href="https://doi.org/10.1073/pnas.1611122114">a decline in the number of cheetahs</a> of 50% over the past <a href="http://www.catsg.org/cheetah/05_library/5_3_publications/M/Myers_1975_Cheetah_in_Africa.pdf">forty years</a>. </p>
<p>In Zimbabwe <a href="https://doi.org/10.5281/zenodo.158911">cheetahs depended heavily on private land</a>, but the amount of private land <a href="http://doi.org/10.1080/03057070.2010.485789">has been reduced by 90%</a> over the last 17 years. This loss has been caused by factors like the country’s land reform programme, which was set out to redress the historical imbalances in land tenure resulting from colonial practices. Under the programme, land previously owned privately by large-scale commercial white farmers was distributed to black Zimbabweans. </p>
<p>But it’s becoming clear that privately owned land plays an extremely important role in conservation, as state owned conservation areas alone aren’t enough to keep large species out of danger. A major problem is that the land reform programme was implemented in a chaotic way. This meant that no consideration was given to how to manage the wildlife that had previously lived in the area. The result was a <a href="https://doi.org/10.7717/peerj.1537">dramatic fall in the number of carnivores</a>. </p>
<p>Until 2000, 34% of <a href="http://doi.org/10.1080/03066150.2011.622042">land in Zimbabwe</a> was privately owned, 13% was state owned conservation and forestry areas, and 42% was communal land. The remainder of that was made up of old resettlement areas, state farms and urban developments. Private land supported <a href="https://doi.org/10.5281/zenodo.158911">80% of Zimbabwe’s</a> <a href="https://doi.org/10.5281/zenodo.158912">cheetahs</a>. But since 2000, 90% of this privately owned land is thought to have <a href="http://doi.org/10.1080/03057070.2010.485789">been resettled</a>. Large numbers of subsistence farmers – making enough for their homes but not enough to sell – now occupy these farm spaces.</p>
<p>In instituting the land reform programme, the survival of the species that depended on privately owned land was pitted against the needs of the people to survive off the land. This is a widespread problem, not one confined to Zimbabwe. But the solution could lie in how land reform is planned. Instead of replacing successful wildlife areas with subsistence farming, keeping the wildlife while allowing more people to benefit economically could hold the key. </p>
<h2>What we found</h2>
<p>We recorded animal tracks across 1000 km of unpaved roads on private land that had been resettled, and on adjacent private land that had not yet been resettled. Our aim was to understand how carnivore numbers had been affected by the resettlement process. This <a href="https://doi.org/10.7717/peerj.1537">research</a> allowed us to draw estimates.</p>
<p>Our studies showed that large carnivores (weighing more than 19 kg) such as African wild dogs had high densities on private land. On neighbouring land that had been part of the same conservancy but had now been resettled, we found <a href="https://doi.org/10.7717/peerj.1537">no signs of cheetahs, leopard, lion, African wild dog, or brown hyenas</a>. We did however find very few tracks from spotted hyenas. </p>
<p><a href="https://doi.org/10.5281/zenodo.21001">Similar trends were also evident</a> for all other mammals studied, from baboons to giraffes.</p>
<p>If these trends are representative on a national scale, our models estimated that carnivore populations have declined steeply since 2000 due to land reform. We predicted that the number of cheetahs in Zimbabwe dropped to approximately <a href="https://doi.org/10.7717/peerj.1537">120 individuals</a>. A subsequent nationwide interview survey estimated that only <a href="http://www.wildernesstrust.com/portfolio/zimbabwe-cheetah-conservation-project/">150-170 cheetahs remain</a> across national parks, private land and communal areas. This represents a fall of 85%, thought to be largely due to land reform.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/175393/original/file-20170623-27912-ct1ckt.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=1000&amp;fit=clip"><img alt="" src="https://images.theconversation.com/files/175393/original/file-20170623-27912-ct1ckt.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=754&amp;fit=clip" srcset="https://images.theconversation.com/files/175393/original/file-20170623-27912-ct1ckt.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=600&amp;h=453&amp;fit=crop&amp;dpr=1 600w, https://images.theconversation.com/files/175393/original/file-20170623-27912-ct1ckt.jpg?ixlib=rb-1.1.0&amp;q=30&amp;auto=format&amp;w=600&amp;h=453&amp;fit=crop&amp;dpr=2 1200w, https://images.theconversation.com/files/175393/original/file-20170623-27912-ct1ckt.jpg?ixlib=rb-1.1.0&amp;q=15&amp;auto=format&amp;w=600&amp;h=453&amp;fit=crop&amp;dpr=3 1800w, https://images.theconversation.com/files/175393/original/file-20170623-27912-ct1ckt.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=754&amp;h=570&amp;fit=crop&amp;dpr=1 754w, https://images.theconversation.com/files/175393/original/file-20170623-27912-ct1ckt.jpg?ixlib=rb-1.1.0&amp;q=30&amp;auto=format&amp;w=754&amp;h=570&amp;fit=crop&amp;dpr=2 1508w, https://images.theconversation.com/files/175393/original/file-20170623-27912-ct1ckt.jpg?ixlib=rb-1.1.0&amp;q=15&amp;auto=format&amp;w=754&amp;h=570&amp;fit=crop&amp;dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A leopard carries a wire snare around its waist.</span>
<span class="attribution"><span class="source">Sam Williams</span></span>
</figcaption>
</figure>
<p>The low abundance of wild mammals on resettled land appeared to be linked to the high density of people that now occupy the land. People have cleared the natural vegetation to grow crops and graze livestock, causing habitat loss, fragmentation, and loss of prey for the carnivores. </p>
<p>Bush meat poaching was also rife on private land close to resettled areas. Between 2001 and 2009 over <a href="https://doi.org/10.1017/S0030605310000153">4,000 poachers captured and over 84,000 snares removed</a> in one conservancy. </p>
<p>Land reform didn’t just affect the wildlife. We found that farmers on resettled land, reported levels of cattle predation by large carnivores that were <a href="https://doi.org/10.5281/zenodo.21001">three times greater</a> than that of farmers on neighbouring communal land. This was despite resettlement farmers working harder to reduce predation by taking measures like kraaling (enclosing) their cattle at night or herding their animals during the day.</p>
<h2>Lessons learned</h2>
<p>As land reform programmes progress in other countries, what lessons can be learnt from Zimbabwe’s experiences?</p>
<p>By planning resettlement schemes carefully as opposed to allowing them to develop haphazardly, authorities could focus resettlement in areas of greater agricultural potential. At the same time, it’s important to maintain connectivity within wildlife populations.</p>
<p>Using fencing that <a href="http://doi.org/10.1007/978-1-4614-0902-1_12">cannot be used</a> to make snares could help. Strands of straight fencing wire is often stolen and <a href="https://doi.org/10.1017/S0030605310000153">used for snaring</a>, but other fencing wire materials such as square mesh cannot be easily made into the loops used by poachers. </p>
<p>Importantly, land reform doesn’t have to mean changing land use. Land reform initiatives should maintain wildlife as a land use where it’s suitable, while diversifying land ownership. Leasing resettled land back to the former owners could also benefit wildlife while also retaining expertise and generating <a href="https://www.routledge.com/Evolution-and-Innovation-in-Wildlife-Conservation-Parks-and-Game-Ranches/Suich-Child/p/book/9780415520447">more income</a> for a broader array of people than switching to subsistence farming.</p>
<p>The hope is that integrating community members as stewards of the land and helping them to benefit financially from wildlife, could encourage them to protect rather than poach animals. This will create durable solutions to the land issue.</p><img src="https://counter.theconversation.com/content/79282/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Sam Williams works for University of Venda, and is an Honorary Research Associate at Durham University. He received funding from the Howard G. Buffett Foundation, Sea World Busch Gardens, the Whitley Wildlife Conservation Trust, Marwell Wildlife, Colchester Zoo, and both the Department of Anthropology and St Mary’s College at Durham University.</span></em></p>The land reform programme in Zimbabwe has come at the cost of wildlife and opens up the debate on people versus nature. But there is a way forward.Sam Williams, Honorary Research Fellow in the Department of Anthropology, Durham UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/728112017-02-27T15:26:48Z2017-02-27T15:26:48ZNew puff adder behaviour uncovered: it uses two ways to entice its prey<figure><img src="https://images.theconversation.com/files/157684/original/image-20170221-18624-sjmga1.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=496&amp;fit=clip" /><figcaption><span class="caption">Puff adders display diverse predatory strategies. This shows they have higher cognitive abilities than previously thought.</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>Predators use a variety of strategies to increase the odds of capturing prey. An amazing example involves the use of luring behaviours, which are aimed at increasing a predator’s foraging success by attracting potential prey to within striking range.</p>
<p>Luring behaviours result from an evolutionary adaptation referred to as <a href="http://www.annualreviews.org/doi/abs/10.1146/annurev.es.13.110182.001125?journalCode=ecolsys.1">aggressive mimicry</a>. This typically includes a predator (the mimic), a model organism (the model), and a potential prey (the dupe). A classic example, the <a href="http://onlinelibrary.wiley.com/doi/10.1111/j.1439-0310.1979.tb01022.x/full">North American alligator snapping turtle</a> wriggles a pink, fleshy structure located on the floor of its mouth, which presumably resembles a worm (the model) to deceive fish (the dupes). This attracts fish and facilitates their capture by the turtle.</p>
<p>Luring also takes place on land as we found in a recent study examining the foraging behaviour of free-ranging snakes. Our <a href="http://link.springer.com/article/10.1007/s00265-016-2244-6">study</a> on the foraging in puff adders – one of Africa’s most widespread, iconic, and medically important snake species – is unique in several ways. But more of it later.</p>
<p>As part of our study we used radiotelemetry in conjunction with <a href="https://www.jstor.org/stable/4098590?seq=1#page_scan_tab_contents">fixed videography</a> to study foraging in puff adders. Fixed videography is a technique that involves continuously recording behaviours of subjects for later analysis.</p>
<p>Puff adders are ideal subjects for such studies because they use specific ambush sites where they lie in wait <a href="http://rspb.royalsocietypublishing.org/content/282/1821/20152182">for prey for extended periods</a> (sometimes days or weeks). This allowed us to setup tripod-mounted surveillance videocameras to record foraging of wild puff adders in their natural environment so that we could record natural predator-prey interactions.</p>
<p>We recorded nearly 5,000 hours of puff adder foraging behaviour in the <a href="http://www.dinokengreserve.co.za/">Dinokeng Game Reserve</a> in South Africa’s Gauteng province. It showed that to attract prey to within striking range puff adders used two techniques: they extended their tongues (lingual luring) and also waved their tails (caudal luring), apparently to mimic an invertebrate model such as a worm or caterpillar. </p>
<p>Lingual luring happened solely in response to the presence of frogs indicating that this behaviour is a frog-specific hunting technique. This suggests that puff adders can visually discriminate amphibians from small mammals, lizard, and birds – even at night when most of the hunting takes place.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/157680/original/image-20170221-18646-12z8xvo.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=1000&amp;fit=clip"><img alt="" src="https://images.theconversation.com/files/157680/original/image-20170221-18646-12z8xvo.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=754&amp;fit=clip" srcset="https://images.theconversation.com/files/157680/original/image-20170221-18646-12z8xvo.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=600&amp;h=400&amp;fit=crop&amp;dpr=1 600w, https://images.theconversation.com/files/157680/original/image-20170221-18646-12z8xvo.jpg?ixlib=rb-1.1.0&amp;q=30&amp;auto=format&amp;w=600&amp;h=400&amp;fit=crop&amp;dpr=2 1200w, https://images.theconversation.com/files/157680/original/image-20170221-18646-12z8xvo.jpg?ixlib=rb-1.1.0&amp;q=15&amp;auto=format&amp;w=600&amp;h=400&amp;fit=crop&amp;dpr=3 1800w, https://images.theconversation.com/files/157680/original/image-20170221-18646-12z8xvo.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=754&amp;h=503&amp;fit=crop&amp;dpr=1 754w, https://images.theconversation.com/files/157680/original/image-20170221-18646-12z8xvo.jpg?ixlib=rb-1.1.0&amp;q=30&amp;auto=format&amp;w=754&amp;h=503&amp;fit=crop&amp;dpr=2 1508w, https://images.theconversation.com/files/157680/original/image-20170221-18646-12z8xvo.jpg?ixlib=rb-1.1.0&amp;q=15&amp;auto=format&amp;w=754&amp;h=503&amp;fit=crop&amp;dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Luring is a technique adopted by puff adders to draw prey withing striking range.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<h2>Luring behaviours</h2>
<p>Luring behaviours have been reported previously in other animals. For example, in addition to the alligator snapping turtle, the <a href="http://www.jstor.org/stable/pdf/20065809.pdf">snowy egret</a> and <a href="https://www.jstor.org/stable/1565240?seq=1#page_scan_tab_contents">four</a> <a href="http://www.jstor.org/stable/1562808?seq=1#page_scan_tab_contents">species</a> of <a href="http://www.bioone.org/doi/abs/10.1670/06-016.1">semi-aquatic snakes</a> from North America are known to use their tongues to lure fish. </p>
<p>Caudal luring has also been observed in many species of <a href="http://booksandjournals.brillonline.com/content/journals/10.1163/15685381-00002997">snakes</a>, in some species of <a href="http://0-www.jstor.org.innopac.wits.ac.za/stable/1446599?seq=1#page_scan_tab_contents">lizards</a>, and the aquatic larvae of <a href="http://www.bioone.org/doi/full/10.1093/jisesa/ieu008">some dragonflies</a>.</p>
<p>But our study is the first report two lures in the same organism. It is also the first to report lingual luring in a predator foraging for terrestrial prey – all other cases involved fish as prey. And this is the first record ever of puff adders luring. </p>
<p>We are not sure what puff adders were trying to attract with their caudal-luring since there was never any potential prey in the camera’s field of view. Although we can’t provide conclusive evidence, we believe the reason for this behaviour is to lure prey because it’s been recorded in other <a href="http://onlinelibrary.wiley.com/doi/10.1111/j.1095-8312.2008.01016.x/full">snakes</a> species.</p>
<p>Our study shows that puff adders display diverse predatory strategies and complex decision-making process to catch prey. This demonstrates that they have higher cognitive abilities than most people would expect of a snake. </p>
<p>Second, the puff adder is commonly kept in captivity for antivenin and for public display. Yet neither lingual nor caudal luring has previously been reported for the species. This shows that that even common species of snakes are often not as well-known as commonly assumed. </p>
<p>Clearly, more field studies are needed to unravel the complexity of snake behaviour. Our study illustrates the power of the radiotelemetry-videography combination as a tool for the study of snake behaviour in a natural setting.</p><img src="https://counter.theconversation.com/content/72811/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Xavier Glaudas receives funding from National Geographic. </span></em></p><p class="fine-print"><em><span>Graham Alexander receives funding from the National Research Foundation and National Geographic.</span></em></p>New research shows that puff adders use two luring techniques to attract prey within striking range.Xavier Glaudas, Post-Doctoral Fellow School of Animal, Plant and Environmental Sciences, University of the WitwatersrandGraham Alexander, Professor of Herpetology, Environmental Physiology and Physiology, Ecology and Evolution, University of the WitwatersrandLicensed as Creative Commons – attribution, no derivatives.